The invention relates to a device for shape-forming the end region of a workpiece, especially for cold-press shape-forming of a pipe end region. It is known to set in compression a workpiece by means of a first hydro-dynamically actuable force transmission element and to shape-form the end region via direct or indirect application of force thereagainst by a second hydrodynamically actuable force transmission element. The concept of hydro-dynamically actuable force transmission elements comprehends a body which is actuable in a hydraulic and/or pneumatic manner. In connection with the highest force which is required for the shape-forming of a workpiece, a hydraulic actuation is chosen specifically for this purpose.
DE 195 11 447 A1 discloses a device adapted for shape-forming a pipe end region. This device includes a recess for exchangeable jaws operable to set the pipe in compression. By means of a first hydraulically actuable piston, the jaws are driven under pressure in order to compressively engage the pipe. The first piston comprises a central through opening in which a piston rod of a second hydraulically actuable piston is guidably disposed. The two pistons are in this manner coaxially movable within one and the same housing serially one behind the other.
The piston rod of the second piston, which is provided with a shape-forming tool, can effect application of a force on the pipe end region, in view of the fact that the piston rod extends through the central, end-to-end continuously open, opening in the first piston, whereby the pipe end region is shape-formed in the axial direction. In this manner, the end region deforms in correspondence with the geometry of the shape-forming tool and the jaws.
In a special configuration, the known device comprises a three-part housing. A first housing portion has a first bore in which the first, annularly shaped, piston is movably guided with its sleeve and has a second bore in which the second piston with its piston rod is movably guided. The second bore has a relatively smaller diameter than the first bore. In this manner, a stop or shoulder for engaging the sleeve of the first, annularly shaped, piston is formed which defines the maximum return position of the first piston. A hydraulic fluid can be introduced for actuating the first piston between the stop or shoulder and the piston sleeve. A further portion of the three-piece housing forms with the first housing portion a threadable housing end piece which comprises a cylindrical bore for guiding the end piece of the second piston. The first housing portion forms a stop or shoulder in the actuation direction of the second piston. A hydraulic medium can be introduced between the stop or shoulder and the second piston in order to effect a return movement of the second piston after the shape-forming of the pipe. The corresponding hydraulic space for receipt of the hydraulic fluid is sealed off relative to the first hydraulic space between the sleeve of the first piston and its rearward stop or shoulder. The third portion of the three-piece housing forms the receiving portion for the jaws and the forward portion of the first and the second pistons or, respectively, the shape-forming tool. The shape-forming tool is configured and connected with the forward end region of the piston rod of the second piston such that, during return movement of the second piston, the first piston is correspondingly brought along and the jaws are thus released from their compression position. In this connection, the central through opening of the first piston comprises a rearward stop or shoulder. The shape-forming process performed by the known device disclosed in DE 195 11 447 A1 is, to this extent, burdened with disadvantages in that a control of the course of the shape-forming process from the beginning to the end thereof as well as a monitoring of the tool and the pipe to be shape-formed before the beginning of the shape-forming process is neither provided for nor possible due to the coupling of the two pistons during their return movements.
The invention provides a solution to the challenge of making available a device for shape-forming a workpiece end region which makes possible a better control of the shape-forming process.
The solution to this challenge is revealed in the advantageous embodiments and further configurations of the invention as set forth in the patent claims which follow this description.
In this connection, the invention initially provides, in a first embodiment, that, between the first force transmission element and the second force transmission element, a first pressure space is arranged communicated with a first pressure connector and that the second force transmission element has a second pressure space, communicated with a pressure connector, arranged relative thereto such that the introduction of a pressure medium into the second pressure space drives the second force transmission element in the compression and shape-forming direction. During the forward displacement of the second force transmission element to set the workpiece in compression, the pressure exerted by the pressure medium in the first pressure space is maintained via blockage of the first pressure connector, whereby, upon reaching a predetermined overpressure, the pressure medium is released from the first pressure space, so that the second force transmission element moves relative to the first force transmission element, which remains in its workpiece compressive engagement position, to thereby effect shape-forming of the workpiece and, after the shape-forming of the end region of the workpiece, the second force transmission element is moved rearwardly to its start position by a renewed introduction of a pressure medium in the first pressure space and, by means of a special drive, the first force transmission element is moved correspondingly therewith back into its start position.
In this connection, the advantage is provided that, by reason of the pressure controlled release of the pressure medium in the first pressure space following the reaching of the overpressure during the forward displacement of the second force transmission element, the workpiece compressive engagement pressure is uniformly maintained at the required value. The required pressure need only be maintained so long as is necessary. In this manner, an unnecessarily high pressure, and an unnecessarily long time period for the maintained pressure and the therewith connected unnecessary loss of performance and high temperature development, are avoided in an advantageous manner. After completion of the shape-forming process, the second force transmission element is movable in an active manner back into its start position.
In accordance with one embodiment of the invention, it is provided that a third pressure space with a connection to a third pressure connector is provided as a drive for the return movement of the first force transmission element. Alternatively, the drive for the return movement of the first force transmission element can, however, be additionally configured as a return spring.
In accordance with an embodiment of the invention, it is provided that the start position of the first force transmission element is defined between the housing and a first force transmission element stop or shoulder. By fixedly positioning the first force transmission element in its start position as well as, also, by selection of the start position of the second force transmission element, the relative displacement movement path between the second and the first force transmission elements required for the shape-forming process is constructively laid out.
In accordance with embodiments of the invention, sensors are provided which recognize the inserted workpiece as well as monitor the respective position of the first force transmission element to determine whether the first force transmission element has again been returned into its start position. In this connection, it is provided, in a case-by-case manner, that before the start of the shape-forming process, it can be automatically determined whether a suitable compression and/or shape-forming tool is available and/or is properly positioned, whereby the availability and/or the proper position of the shape-forming tool can be determined by a non-contact distance measurement effected by a sensor. Additionally, it can be provided that, via a sensor, the start position of the shape-forming tool and the position thereof during the shape-forming process can be sensed.
In a further development of the inventive device, it can be provided that the required relative movement path for the shape-forming process between the first force transmission element and the second force transmission elementxe2x80x94that is, the so-called shape-form length Lxe2x80x94is adjustably settable in a first process step, such that the first force transmission element is movable away from the second force transmission element by introduction of a pressure medium into the first pressure space, whereby, via introduction of a pressure medium in the second pressure space, the compression process and the shape-forming process follow thereafter as described. A pressure medium is, accordingly, introduced into the first pressure space both for actuation of the first force transmission element as well as for releasing the second force transmission element, whereby there is obtained the advantage of a still further improved control possibility for the shape-forming process.
In this connection, it can be provided that the length of the first pressure space between the first actuation surface and the second actuation surface is adjustably set before the shape-forming of the workpiece in order to set the desired defined work path. Following therefrom, the two force transmission elements can be moved while maintaining a constant relative position to one another until the workpiece has been set in compression. As a further consequence thereof, the second force transmission element is movable precisely along the predetermined length of the pressure space against the first force transmission element, so that the compressively engaged workpiece is shape-formed by a movement along this length. The shape-forming process is brought to an end in particular due to the engagement of the first actuation surface and the second actuation surface of the first pressure space with one another.
In a further configuration of the device, the length of the pressure space is directly or indirectly measurable in order to adjustably set the length. In particular, the length is indirectly measurable via a distance sensor which is oriented toward a surface whose distance from the distance sensor varies as a function of the length of the pressure space. A surface of this type is, for example, configured as an outwardly expanding conical outer surface of the first force transmission element. It is advantageous if a non-contact measuring distance sensor is deployed.
A non-contact measuring sensor is provided which emits a signal in dependence upon whether the workpiece to be shape-formed is in a start position in which it can be compressively engaged and/or shape-formed. The sensor is, in particular, a distance sensor which measures the distance in a measurement direction to the most closely adjacent object. Such sensors, including, for example, a laser emitting sensor, are known.
In this event, the workpiece need only be disposed in the start position in order to produce the signal. In particular for controlling the compression process and/or the shape-forming process, a control is provided which is connected via a signal connection with the sensor. By means of the transmission of a signal to the control, especially, an automatic signal, the compression process and/or shape-forming process is initiated.
In particular, non-contact measurement of a dimension of the workpiece to be shape-formed or, respectively, a measurement value, is performed which provides a clear measurement of the dimension of the workpiece to be shape-formed. If, for example, a pipe is to be shape-formed, the possibility is available to measure the pipe diameter. This permits, before the start of the compression process and/or the shape-forming process, a monitoring of whether a workpiece with the desired dimensions for shape-forming is standing ready. If the proper workpiece has not been brought into a start position or there is, in any event, no workpiece at all in the start position, a start signal is correspondingly also not produced. An unintended actuation of the shape-forming device or, respectively, the working of the workpiece with false dimensions can thus be avoided in this manner. An important advantage lies in the fact that security measures for protecting the operating personnel can be maintained in a simple manner and, at the same time, damage of the device such as through the disposition of too large a workpiece therein, can be prevented.
Furthermore, it is suggested that, before the start of the compression process and/or the shape-forming process, that it be automatically determined whether a suitable compression and/or shape-forming tool is available and/or is properly positioned. In this connection, it is particularly suggested to provide a non-contact measuring sensor which generates a signal as a function of whether a suitable compression and/or shape-forming tool is available and/or is properly positioned. A shape-forming tool recognition in this manner can be combined with the above-described sensor to produce a start signal in order to achieve still greater assurance against false actuation and false functioning. In particular, the same sensor can be used for measuring the start position and for measuring the availability and/or the positioning of the shape-forming tool. In this event, the availability and/or the proper positioning of the shape-forming tool is, preferably, initially measured or, respectively, pre-set.
Moreover, it is further suggested to provide a sensor which measures in a non-contact manner the progression or continuing movement of the shape-forming of the workpiece. In particular, a control can be further provided which receives a signal of the sensor, and which, after the shape-forming has been adequately performed, effects the end of the shape-forming process.